The clean face of tomorrow’s urban public transportation
Getting ready for the future with Damen’s carbon neutral, fully electric waterbus.
Damen’s 24-metre Waterbus has already proved its worth as an efficient mode of urban public transport. They are in operation in the Belgian city of Antwerp, for example, where improved infrastructure and reduced pressure on roads are perhaps the two most significant benefits of this water-based form of public transport.
However, in response to the ambitions of an ever-growing number of local governments working towards zero carbon emissions, Damen is transforming the success of the, up until now, diesel-powered Waterbus into a future-proof public transport solution. “We are offering the same proven design of the Waterbus 2407 in a fully electric configuration,” says Jan van Ooijen, Design & Proposal Engineer at Damen.
Proven COTS technologies
The feasibility of such a battery-operated passenger ferry can be attributed to advances in battery technology. “It is comparable to electric cars. Because they had low distance capabilities when they first came on to the market, no one wanted one. Now though, you can do the same distance, at the same speed, as a conventional car. Now it is desirable.”
A key part of the project was to use proven Commercial Off-The-Shelf (COTS) techniques that are already in use to speed up the design process as well as keeping costs down.
We didn’t have to reinvent the wheel. If we did that, then we lose the advantage of volume and so the cost goes up. So we are re-using existing technology based on an electric road bus.
In Damen’s Electric Waterbus design the hull is fitted with batteries, distribution network and electric propulsion.
Long battery life
The vessels are designed to operate for sixteen hours per day and be charged two times an hour. For those readers not up to speed with battery technology, this considerable amount of charging calls for a battery with a long lifespan. “We have selected a high-end lithium battery with a long lifespan,” notes Jan. “They are quite heavy, but they do have the required longevity.” Charging takes place using two >600 kw connection chargers contained within a pontoon at shoreside.
Although the repetitive nature of public transport typically allows energy requirements to be accurately calculated in advance, Jan goes on to say that one particular aspect of the Electric Waterbus design was not so straightforward to predict. “HVAC [Heating, Ventilation and Air Conditioning] is a large energy consumer, but demand fluctuates seasonally. Therefore, the question that we needed to answer was: do we want to power HVAC capacity from the batteries? Or do we want to include another power source?”
One of the first options that was considered was heat pumps. This was quickly side-lined due to the fact that these are quite limited when it comes to water temperature. “This led us to the solution of dedicated seat heating and cooling, instead of concentrating on handling the entire vessel. At the moment, this is still in the engineering stage, but it’s very promising. It is a very efficient process as there is no waste because you apply heating and cooling only when required.”
Electric without compromise
Damen has used the ferry service running between Central Rotterdam and the neighbouring city of Dordrecht to present a proposed operational profile of a fully electric service. Here, as Jan explains, providing a realistic alternative to current diesel-powered vessels was vital. “You won’t be able to get an electric waterbus to market if it causes long delays to an operator’s schedule. We had to solve that by adding more charging power,” he says.
This in addition to the extra infrastructure required to operate an all-electric service does, of course, require considerable initial capital outlay.
However, we can demonstrate that, looking over a twelve-year period there are huge savings to be made.
And with this final statement, Damen is adding two further benefits to its already proven Waterbus design; decreased operational costs and zero carbon emissions.